💍 Ring Size Calculator

How Ring Sizing Works

Ring sizes are ultimately based on a single physical measurement — the inside circumference (or diameter) of the ring — but different countries express that same measurement using different scales. The US/Canada system uses a numeric scale (3 to 13+, often with half sizes), the UK/Australia system uses letters (A to Z+), and most of continental Europe simply uses the circumference in millimeters directly as the size number.

Two Ways to Measure at Home

• Diameter method: if you already have a ring that fits the intended finger well, lay it flat and measure the inside diameter (edge to edge, not including the band's width) with a ruler in millimeters.
• Circumference (string/paper) method: wrap a non-stretchy strip of paper or string snugly around the base of the finger, mark the point where it overlaps, then lay it flat and measure that length in millimeters.

Tips for an Accurate Fit

• Measure at the end of the day when fingers are typically at their largest, and avoid measuring when your hands are cold (fingers shrink in the cold)
• Wider bands generally need to be sized slightly larger than thin bands to fit the same finger comfortably
• If you're between two sizes, most jewelers recommend sizing up rather than down

❓ Frequently Asked Questions